Total 51nod 1352 episodes (extended Euclidean)

Topic Link: Portal

Test instructions: Slightly

Analysis:

It's easy to get an equation a*x + b*y = N + 1

This equation can be extended gcd to find gcd,x and Y, and then we find a minimum of more than 0 x,a*x the first satisfies the set Firstset, the remainder of the N-firstset set can be directly in addition to the LCM (A, B) (A and a least common multiple) statistics of the quantity.

The code is as follows:

#include <stdio.h> #include <string.h> #include <iostream> #define LL long longusing namespace std;    ll EXGCD (ll A, ll B, LL &x, ll &y) {ll r,t;        if (b==0) {x=1;        y=0;    return A;    } r=exgcd (B,a%b,x,y);    T=x;    X=y;    Y=t-a/b*y; return r;}    int main () {int t;    scanf ("%d", &t);        while (t--) {LL ans = 0;        LL N, A, B;        LL Xx,yy,d,r;        scanf ("%i64d%i64d%i64d", &n, &a, &b);        D=EXGCD (A, B, XX, yy);        if ((((N + 1)% B)% d! = 0) ans = 0;            else {LL LCM = A * B/D;            xx = xx * (((N + 1)% B)/d);            R = b/d;            xx= (xx% r + R)% R;            if (xx = = 0) {xx = lcm/a;                } if (XX * A > N) {ans = 0;                printf ("%i64d\n", ans);            Continue            } ans + = ((N-XX * A)/LCM);        ans++;    } printf ("%i64d\n", ans); } return 0;} 

Total 51nod 1352 episodes (extended Euclidean)